Lecture Jure Demsar

Roster

Ultrafast studies of photoinduced melting of the order parameter in superconductors and CDW systems

Date:

Fri Nov 21, 2008

Start:

10.00

Location:

FWN-Building 5114.0004

Host:

Paul van Loosdrecht

Telephone:

+31 50 363 8149

Abstract

In superconductors (SC), it has been known for decades that photoexcitation with an intense laser pulse can non-thermally destroy the superconducting ground state. The energy required to destroy superconductivity should be equal to the condensation energy (energy difference between the free energy of the SC and normal states at T = 0 K) if all the absorbed optical energy is kept in the electronic subsystem during the process of suppression of superconductivity.

Recent experiments on conventional as well as cuprate [2] superconductors show, however, that the energy required to melt the SC condensate is substantially higher than the thermodynamically measured condensation energy. By studying the possible energy relaxation pathways insight into the origin of pairing can be gained.

Similar studies on low dimensional CDW systems have been recently performed [2], showing that non-thermal melting of the electronic modulation can be achived. Interestingly, the results suggest that during the process of melting and subsequent sub-picosecond recovery of the electronic system the lattice remains nearly unperturbed. Only on longer timscales after perturbation the relaxation of the CDW state could be described by coupled modulation of the electron density and the underlying lattice.